Network and Using it (4)

• Topics to learn about

  • Networks
  • Network issues and communication
• Networks


  • Routers
  • Common network devices (NICs, hubs, switches, bridges)
  • Wi-Fi and Bluetooth
  • Cloud computing
  • Intranets, extranets and the internet
  • LANs, WLANs and WANs
• Network issues and communication


  • Security (including passwords, types of authentication)
  • Anti-malware
  • Electronic conferencing
• Network


  Connects computers and other digital devices together and allows them to share data and resources
• Example uses of networks


  • Computer to computer communication
  • Computer to devices such as printer, mice and keyboards
  • Mobile phone network
  • Smart televisions
  • Tablets and media players downloading videos and music and playing them through external devices such as speakers and digital projectors
• Largest network


  The internet
• Common network devices and terms

  • Network interface card (NIC)
  • Media access control (MAC) address
  • Internet protocol (IP) address
  • Data packet
• Network interface card (NIC)


  Allows a device to connect to a network by turning binary data into an electrical signal
• MAC address


  Uniquely identifies a device when it is connected to a network
• IP address


  Identifies the location of a device on a network
• IP address versions


  • IPv4
  • IPv6
• IPv4


  32-bit address written as four groups of eight bits in denary format
• IPv6


  128-bit address written as eight groups of hexadecimal digits
• Data packets


  Data is moved around networks in the form of data packets which contain information like sender's IP address, receiver's IP address, sequence/identity number, packet size, and number of packets in the message
• Hubs


  Hardware devices that connect multiple devices together to form a LAN, broadcasting data packets to all connected devices
• Switches


  Intelligent versions of hubs that store MAC addresses and direct data packets to the correct destination device
• Differences between hubs and switches


  • Both use data packets
  • Hubs broadcast packets to all devices, switches send to specific device
  • Security is lower with hubs than switches
  • Switches use MAC addresses to locate destination device
• Bridges


  Devices that connect one LAN to another LAN using the same protocol, allowing them to function as a single LAN
• Routers


  Used to route data packets from one network to another based on IP addresses, joining a LAN to the internet
• How a router works


  Receives data packet, inspects IP address, routes to local network or transmits to external network based on routing table
• Routing table


  Contains information about the router's immediate network and other nearby routers, allowing it to determine where to send data packets.
• Bluetooth


  Sends and receives radio waves in 79 different frequency channels, automatically detecting and connecting devices while avoiding interference
• Wi-Fi


  Sends and receives radio waves in 2.4 GHz and 5 GHz frequency bands, offering faster data transfer rates, better range, and better security than Bluetooth
• Cloud computing (storage)


  Method of data storage where data is stored on remote servers in multiple locations for redundancy, allowing clients to access data at any time
• WPAN


  Wireless personal area network
• Wi-Fi


  • Sends and receives radio waves in several different frequency bands - 2.4 GHz and 5 GHz are the most common
  • Each band is further split into channels
  • The 5GHz band has a faster data transfer rate but a shorter signal range
  • Offers much faster data transfer rates, better range and better security than Bluetooth
• Wi-Fi-enabled device


  A computer or smartphone that can access the internet wirelessly at any access point (AP) or 'hot spot' up to 100 metres away
• Cloud computing


  • A method of data storage where data is stored on remote servers - there may be thousands of servers in many different locations
  • The same data is stored on more than one server in case of maintenance or repair, allowing clients to access data at any time
  • The physical environment of the cloud servers is owned and managed by a hosting company
• Cloud storage


  Instead of, or in addition to, saving data on a local hard disk or other storage device, a user can save their data 'in the cloud'
• Cloud storage systems


  • Public cloud - customer/client and cloud storage provider are different companies
  • Private cloud - storage provided by a dedicated environment behind a company firewall; customer/client and cloud storage provider are integrated and operate as a single entity
  • Hybrid cloud - combination of public and private cloud; some data resides in the private cloud and less-sensitive/less-commercial data can be accessed from a public cloud storage provider
• Companies that transfer vast amounts of confidential data from their own systems to a cloud service provider are potentially relinquishing control of their own data security
• There is a risk that important and irreplaceable data could be lost from cloud storage facilities
• Actions from hackers (gaining access to accounts or pharming attacks, for example) could lead to loss or corruption of data
• Users need to be certain that sufficient safeguards exist to overcome these potentially very harmful risks
• In 2019, there were a number of breaches of cloud security
• Pharming attacks


  • Redirects internet users to a fake or malicious website set up by, for example, a hacker; redirection from a legitimate website to the fake website can be done using DNS cache poisoning
  • The creator of the malicious code can gain personal data, such as bank details, from the user
  • Often the website appears to come from a trusted source and can lead to fraud and identity theft
• Network types


  • Local area network (LAN)
  • Wireless local area network (WLAN)
  • Wide area network (WAN)
• If a number of LANs are joined together using a router, then they can form a WAN
• The network of ATMs (automated teller machines) used by banks is one of the most common examples of the use of a WAN
• WANs usually make use of some public communications network (such as telephone lines or satellites), but they can use dedicated or leased communication lines, which can be less expensive